Electrical transformer.



STATES PATENT OFFICE.

EMIL E'AEFELY, 0F BASEL, SWITZERLAND, ASSIGNOR TO WESTINGHOUSE ELECTRICAND MANUFACTURING COMPANY, A CORPORATION 0F PENNSYLVANIA.

ELECTRICAL TRANSFORMER.

Specification of Letters Patent.

Patented Mar. 2, 1915.

Application led January 10, 1912. lSerial No. 670,532.

' To all w71 om it may concern:

. iron core by means ofcylindrical sleeves composed of tough paper lorcardboard, either alone or in, combination with mica, or composed of.mica only, these sleeves being disposed around the core, and betweenthe. high and low tension windings. As both windings are usually ofcircular form, it has'been usual to make the sleeves likewise ofcircular form, all the component parts of the .transformer being thuscoaxially arranged'. The unavoidable =losses 'in the windings and in themagnetizable iron are converted into heat which is conducted away fromthe points at which it is produced by meansA of-a cooling mediumconsisting, in the case of comparatively low voltages, either of air orof oil, and in Athe case of high volty ages, exclusively of oil. Thewindings and other parts of an oil-cooled transformer are inclosed by acasing iilled with oil, the heaty generated at various points beingtransmitted to the oil, with the result that the portions of the oilwhich are first influenced by heat expand, becoming lighter andconsequently rising, while the colder and consequently denser portionsof the oil press downward. Inpthe upper end of the casing there isusually provided a cooling dev1ce cons1st ing. of a serpentine pipethrough whlch cold water is passed, so that the entire operatlon isconstantly repeated,.thatis tosay, there 1s a continuous circulationofthe oil as long as the Itransformer is loaded and generates heat.

Insulating sleeves of the usual kind,as a matter of course, tend to takeup heat from the oil whichsurrounds them; but they also generate ontheir own account a certain amount of heat due to dielectric hysteresls,such heat being greater, the higher the potential difference in thetransformer-and the thicker the walls of the sleeves. From the precedingremarks it will be clear thatit would ge a considerable advantage if theoil were caused to How over and to cool both theinternal and theexternal surfaces of the insulating sleeves, as it is at these placesthat the greater part of the heat is generated. As it is necessary thatthe transformer should be as compact as possible one winding is usuallyplaced close to the insulating sleeve and only a small clearance is lefton the other side between the sleeve and the other winding. Under suchcircumstances it may easily happen that the oil gets locked in thisclearance, that is to say, that 'on account ofthe great frictionalresistance it cannot ascend, no matterhow hot it may become, with theresult that the .insulating sleeve, becoming overheated, swells andbecomes soft, thus giving rise to the risk of rupture andshort-circuiting from the hightension to the low-tension winding of .thecore, lt may moreover occur that small quantities of water find theirway from the cooling serpentine pipe into the oil, through leakage orsweating. This water traveling in the oil-circuit finds its way into theclearance above mentioned, where it may give rise to the rupture of theinsulating sleeve.

i Now the present invention relates to an insulating sleeve of polygonalcross-section, that is especially suitable forloil transformers exposedto high electromotive forces, and that enables the cooling medium to becirculated along both the inner and the outer side of the sleeve, while,moreover, it affords mechanical support to the windings; the arrangementbeing such that the places at which the sleeve comes in contact with theinner and outer windings between which it is interposed in atransformer, do not lie exactly opposite to one another, butaredisplaced in relation to each other to the extent of half the length ofa side of the sleeve. For the said lpurpose of supporting the windingsof the transformer, the sleeve itself is rigid and remains so forever,and forms a homogeneous hollow bod; closed in itself; it consistsofpaper or any equivalent textile fabric which is wound in a continuouslength under high pressure on a prismatic mandrel corresponding to thedesired form of cross section of the sleeve, till the necessarythickness of the sleeve is obtained.

The accompanying drawing shows in cross section three examples ofapparatus made in accordance with my invention. In.

each o f the forms of the apparatusshown. in the 'drawing, an insulatingsleeve 1 of olygonal crosssection .or prismatic form is i interposedbetween coils 2 and of curved or circular cross-section.

In Figure 1,` the insulating sleeve is of octagonal cross section, whilethose shown in Figs. 2 and 3. have respectively decagonal anddodecagonal cross sections.

The places at which the inner and outer coils come in contact with eachof the sleeves shown are displaced in relation to each other to theextent of half the length of a sideof the sleeve, the arrangement beingsuch that the inner'` winding is in contact with the sleeve in themiddle of each side, while the outer winding bears against the angles ofthe sleeve; there consequently occurs at each angle on the interior andat each side on the exterior a spandrel that gives sufiicient play vforthe circulation of the oil and for the cooling of the sleeve and of thewindings separated thereby. 4VWith a sleeve of given dimensions, theless the number of its sides I and angles, the greater'is the crosssection of the spandrel-like spaces. It is a great advantage to have thesleeve support the mechanical rigidity and support without which theymight easily suffer damage in the case of considerable variations ofload,

short-circuits, and the liie.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is 1. Electrical apparatus comprising a coil of curvedcross-section and an adjacent insulating member of polygonal crosssection, said coil engaging the insulating member at its vertices.

2. Electrical apparatus comprisingr a coil of curved cross section, anda concentrically disposed insulating member of polygonal cross-section,whereby ventilating'spaces are provided between. adjacent surfaces ofthe coil and ,insulating member.

3. Electrical apparatus comprising a plurality of concentric circularcoils and an insulating sleeve of polygonal cross-section interposedbetween and supporting the coils,

the outer coil engaging the insulatingV sleeve at its vrtices.

4. Electrical apparatus comprising a plurality vof `concentric circularcoils and an insulating sleeve of polygonal cross section interposedbetween the coils, the inner coil engaging the insulating sleeve 'atpoints intermediate its vertices.' Y

5. Electricalapparatu's comprising a plurality of coils arranged onewithin the other,

and an insulating sleeve of polygonalcross section interposed betweenand supporting the coils, the circumscribed coil engaging the insulatingsleeve at its vertices and the inscribed coil engaging the sleeve atpoints intermediate its vertices. j

6. Electrical apparatus comprising a plurality of coils arranged onewithin the other, and an insulating slee\'e"interposed between andsupporting the coils, the said coils and sleeve being relatively curvedand polygonal in cross-section to provide spandrels between the sides ofthe sleeve and the circumscribed coil and between the vertices of thesleeve and the inscribed coil.

7. Electrical apparatus comprising a plurality of curved cross sectionalcoils arranged one within the other, and an insuform, and interposedbetween and supporting, the coils, whereby Ventilating spaces areprovided between adjacent coil and sleeve surfaces, 'the Ventilatingspaces on opposite sides of said sleeve being displaced in relation toone another. Y

8. Electrical apparatus comprising a plurality of curved cross-sectionalcoilsl arranged one within the other, and an insulating sleeve ofpolygonal cross-sectional form interposed between the coils, wherebyventilatingspaces are provided between adjacent ccil and sleevesurfaces, the ventilating spaces on opposite sides of said sleeve beingdisplaced in relation to one another to tlje extent of substantiallyhalf the length of one: side of the polygon.

I n testimony whereof .I have signed'A my name to Ythis specification inthe. presence of two subscribing witnesses. l

l EMIL HAEFELY.

Witnesses:

Hans Sricxnnnnem. GEORGE Glrronn.

